The 28-year-old prince was in a mischievous mood, dodging pretend blows meted out with a rolling pin by his charity’s co-founder, Lesotho’s Prince Seeiso, before the pair settled down to learn the art of making mokoenya, a Sotho form of doughnut cooked in boiling oil.

When they were done, the third-in-line to the throne served the sizzling treats up to the assembled British press - laughing delightedly as fingers and tongues were burned.

Earlier, he attended a sign-language class where he was shown how to write out his name.

Prince Harry learns sign language from deaf children during a visit to the Kananelo Centre for the deaf (Getty Images)

His three-day visit to the Southern African mountain kingdom is one of a series he has made over the past nine years since he first visited on his gap year in 2004. He founded Sentebale, meaning “forget me not” in Sotho, with Prince Seeiso, in memory of their late mothers, in 2006.

Today, the charity supports tens of thousands of children across the impoverished country who are either suffering from HIV/Aids or orphaned or have physical disabilities. It has ambitious plans to expand to five more countries and quadruple its income.

Prince Harry learns sign language from deaf children during a visit to the Kananelo Centre for the deaf (Getty Images)

Its new chief executive, Cathy Ferrier, told recently how Prince Harry was so closely involved in the organisation that while on four-month deployment as a helicopter pilot in Afghanistan that ended in January, he emailed once a fortnight to keep up to date with developments.

Princes Harry and Seeiso visited Kananelo Centre for the Deaf, in a rural setting outside the capital Maseru. It is one of just two schools for deaf children in the country, reached by a rutted dirt track and set amid maize fields and a soaring mountain backdrop.

In a series of single-storey, breeze block huts, a group of Roman Catholic nuns educate 85 students aged between five and 22. Since 2008, Sentebale has provided 70 per cent of the school’s running costs.

They were greeted by hundreds of children from Kananelo and neighbouring schools who surged around them, ululating and clapping their welcome when it came.

Prince Harry and Prince Seeiso were led into a classroom for a lesson in rudimentary sign language. Prince Harry furrowed his brow in concentration as he was shown how to arrange his hand in the words “mother, father, sister, brother”, on occasions corrected by 14-year-old Nondos Chabalalan.

“I’m never going to get this right,” he complained to a laughing Prince Seeiso, mock-wiping his brow.

(Tim Rooke / Rex Features)

Prince Seeiso asked the pupils to show Prince Harry the word for “ginger” — the prince retorted that he should be shown the world for “bald”.

As the two princes teased each other, a heart-rending wail split the classroom from a little boy at the back of the room who could not see.

Limpho Nokoana, aged seven, was lifted up by the prince’s private secretary and carried to the front of the room where he sat on Prince Seeiso’s knee and was fed Werther’s Originals.

Prince Harry observed ruefully as another little boy walked past humming, his mouth full of butterscotch: “In my school, you couldn’t just walk around eating sweets.” The princes were later led into another room where an overflowing plastic wash basin of dough awaited them. Handed aprons, Prince Harry opted for a purple one with Paddington Bear on, leaving Prince Seeiso to struggle into a white lace one fringed with pink ribbons and bows.

“What are we making, pizza?” Prince Harry enquired as he was handed a rolling pin and some dough, pretending to hit Prince Seeiso over the head with the former.

(Getty Images)

They were told they were making mokoenya, a Sotho sweet bread cooked in boiling oil.

The princes were shown how to roll the dough then use a plastic cup to cut out circles which were then dropped into boiling oil. When they were cooked, Prince Harry handed his handiwork out to the assembled journalists — one of whom received a glare from the prince when he remarked that they were “a little burned”.

Later, they visited St Bernadette’s Centre for the Blind in urban Maseru, which looks after 69 pupils. As Prince Harry walked along shaking hands with and talking to the assembled children, Prince Seeiso told the Telegraph that their aim was to help eradicate the stigmatism of disability in Lesotho, as well as providing financial support.

“I hope that with all these issues, HIV, mental and physical disabilities, we are beginning to see a difference,” he said.

“If we do our work well, Sentebale will not be needed in 20 years because there will be no vulnerable children left.”

Prince Harry meets 15 year old orphan Keneuoe and partially sighted children at St Bernadette's Centre for the blind (Getty Images)

He said that he had seen none of the signs of the Party Prince, as he has been dubbed since photographs of him half-naked in Las Vegas emerged last year.

“For me, when he first came out to Lesotho, he was a relatively young chap straight from school,” he said.

“Over the years and being allowed to come here and be himself, I have seen that boy grow into a solid man with a proper vision about what he wants to do not only in Lesotho but in life.”

Prince Harry was due to address a group of businessmen and politicians at a Johannesburg dinner organised to raise £2.5m for a new Sentebale recreational centre in Lesotho for children with HIV/Aids.